Wear-resistant flexible sheet material and a method for its manufacture

Abstract

A wear-resistant flexible sheet material, suitable for use as outer soles on footwear, is produced by pressing reconstituted polyurethane foam sheets in the substantial absence of air at temperatures above 150° C. The sheets should have a density exceeding 15 lb/ft 3 and are further densified by the hot pressing. The sheets are preferably pre-heated to 175°-210° C. and pressed under a pressure of 5 to 30 tons/ft 2 for periods of up to 5 minutes. The sheets may be embossed or smooth surfaced and may contain pigments, plasticizers and other additives.

We claim: 
     
       1. A process for making wear-resistant flexible sheet material comprising the steps of: providing a sheet of dense flexible reconstituted polyurethane foam material having a density exceeding about 15 lb/ft 3  ;   and subjecting said sheet to a pressure of about 5 to 30 tons/ft 2  at a temperature above about 150° C. in the substantial absence of air whereby said sheet is densified and its wear resistance enhanced.   
     
     
       2. The process of claim 1 wherein said pressing is carried out at a temperature in the range of about 150° to 250° C. 
     
     
       3. The process of claim 1 wherein said sheet is preheated to a temperature in the range of about 150° to 250° C. for a period of about 1 to about 5 minutes prior to pressing. 
     
     
       4. The process of claim 1 wherein said pressing is carried out for a period of 1 to 4 minutes depending on the thickness of said sheet. 
     
     
       5. The process of claim 1 wherein the polyurethane is of the polyether or polyester type. 
     
     
       6. The process of claim 1 wherein a material selected from the group consisting of a flame-retardant, a colorant, a deodorant, a fungicide and a plasticizer is added to the reconstituted foam starting material. 
     
     
       7. Wear-resistant flexible sheet material made by the process of claim 1. 
     
     
       8. A process for making wear-resistant flexible sheet material comprising the steps of: providing a sheet of dense flexible reconstituted foam composed at least predominantly of polyurethane;   heating said sheet to a temperature in the range of about 150° to 250° C.;   and compressing said sheet at said temperature between heated platens to the substantial exclusion of air from all but peripheral portions of said sheet and under a pressure in the approximate range 5 to 30 tons/ft 2  for a period of about 1 to about 4 minutes to a final sheet thickness in the approximate range of 1.2 to 18 mm.   
     
     
       9. The process of claim 8 wherein said sheets are heated to a temperature of 175° to 210° C. over a period of 1 to 5 minutes prior to said pressing. 
     
     
       10. A process for making wear-resistant flexible sheet material comprising the steps of: providing a sheet of dense flexible reconstituted polyether type polyurethane foam material having a density exceeding about 15 lb/ft 3  ; and   subjecting said sheet to a pressure of about 5 to 30 tons/ft 2  at a temperature above about 150° C. in the substantial absence of air whereby said sheet is densified and its wear resistance enhanced.   
     
     
       11. The process for making wear-resistant flexible sheet material of claim 10, wherein the temperature is in the range of 150° to 250° C. 
     
     
       12. The process for making wear-resistant flexible sheet material of claim 10, wherein the polyurethane foam material is preheated at a temperature of about 150° to 250° C. prior to the pressure treatment. 
     
     
       13. The process for making wear-resistant flexible sheet material of claim 10, wherein the reconstituted polyurethane foam material is fully cured. 
     
     
       14. Wear-resistant flexible sheet material made by the process of claim 10.